How does Keras handle multilabel classification?

In short Don’t use softmax. Use sigmoid for activation of your output layer. Use binary_crossentropy for loss function. Use predict for evaluation. Why In softmax when increasing score for one label, all others are lowered (it’s a probability distribution). You don’t want that when you have multiple labels. Complete Code from tensorflow.keras.models import Sequential from … Read more

How to stack multiple lstm in keras?

You need to add return_sequences=True to the first layer so that its output tensor has ndim=3 (i.e. batch size, timesteps, hidden state). Please see the following example: # expected input data shape: (batch_size, timesteps, data_dim) model = Sequential() model.add(LSTM(32, return_sequences=True, input_shape=(timesteps, data_dim))) # returns a sequence of vectors of dimension 32 model.add(LSTM(32, return_sequences=True)) # returns … Read more

How to tell Keras stop training based on loss value?

I found the answer. I looked into Keras sources and find out code for EarlyStopping. I made my own callback, based on it: class EarlyStoppingByLossVal(Callback): def __init__(self, monitor=”val_loss”, value=0.00001, verbose=0): super(Callback, self).__init__() self.monitor = monitor self.value = value self.verbose = verbose def on_epoch_end(self, epoch, logs={}): current = logs.get(self.monitor) if current is None: warnings.warn(“Early stopping requires … Read more

How to check which version of Keras is installed?

Python library authors put the version number in <module>.__version__. You can print it by running this on the command line: python -c ‘import keras; print(keras.__version__)’ If it’s Windows terminal, enclose snippet with double-quotes like below python -c “import keras; print(keras.__version__)”

What is the difference between sparse_categorical_crossentropy and categorical_crossentropy?

Simply: categorical_crossentropy (cce) produces a one-hot array containing the probable match for each category, sparse_categorical_crossentropy (scce) produces a category index of the most likely matching category. Consider a classification problem with 5 categories (or classes). In the case of cce, the one-hot target may be [0, 1, 0, 0, 0] and the model may predict … Read more

What’s the difference between a bidirectional LSTM and an LSTM?

LSTM in its core, preserves information from inputs that has already passed through it using the hidden state. Unidirectional LSTM only preserves information of the past because the only inputs it has seen are from the past. Using bidirectional will run your inputs in two ways, one from past to future and one from future … Read more

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